The present invention relates to sensors which were developed for anti-locking and slip warning systems for vehicles. However, they can also be used for other aims. The sensors compare by electrical means the wheel periphery deceleration with the vehicle linear deceleration, and in the case of an excessive deviation between the decelerations, the sensors provide electrical measured value. In the same way the sensors measure and control the ratio between the wheel periphery acceleration and the vehicle linear acceleration. Simultaneously they can measure and indicate the components of the decelerations and accelerations separately. The sensors can also measure the transversal deceleration of a vehicle and the wheel rotary deceleration when the sensor is arranged so that its axis runs parallel to the wheel axle.
Anti-locking systems for vehicles require reliable sensors in order to achieve greater safety when braking a vehicle. The aim of the sensors is to control the wheel rotary motion and give commands when the brake pressure should be reduced, held constant, or increased.
The disadvantages of the rotational deceleration sensors are that in the case of the regulation or control of anti-locking systems they do not take into account the differing road conditions, that they only react in the case of a certain prefixed and pronounced rotational deceleration and respond late particularly in the case of smooth road surfaces. With such sensors it is also not possible to avoid wheel locking with certainty, because their limit of response must correspond to a wheel rotation deceleration of approximately 10 m/s.sup.2 having regard to road conditions in which good engagement is obtained. However, if for example on a smooth road surface one brakes the wheels slightly below the limit of response, locking of the wheels may occur before the vehicle itsself comes to a standstill, which is decelerated perhaps only at the rate of 2 m/s.sup.2.
A comparison measurement with respect to deceleration between the wheel periphery and the vehicle linear deceleration makes it possible to avoid the disadvantages described.